Method and Device for Reducing Moisture Access to a Foundation

ABSTRACT

A method and a device for reducing or substantially prevent admission of moisture to a space ( 10 ) of a foundation construction of a building the space being sensitive to moisture. The device is characterized by at least one expandable device ( 20 ) intended to be introduced in the space ( 10 ) of the foundation construction. The expandable device ( 20 ) is in an expanded condition intended to fill at least a substantial part of the space ( 10 ).

TECHNICAL FIELD

The present invention relates to a method and a device for reducing or substantially prevent admittance of moisture into a moisture sensitive space of a foundation construction of a building and to thereby prevent moisture and mould damages.

BACKGROUND OF THE INVENTION

Since several hundreds of years back, our living house shave been founded according to the suspended foundation principle or the “creeping” foundation principle, as it may be called, as well. It is an old and experienced construction and it is designed in such a way that there is a ventilated space between the floor construction and the ground, a so called crawl space. The suspended foundations of today normally consist of carrying beams, e.g., reinforced cement beams. Onto the cement beams there are beam and slab floor cassettes comprising wooden beams with over piece and under piece sheets of wood fiber material. The beam and slab cassettes are well heat insulating to reduce the energy consumption of the house. The foundation is ventilated using outdoor air by means of natural draught.

The present requirements for high qualitative insulation leads to that the under side of the floor construction today is colder than in old days. Previously it was also more common that one heated the houses using stoves and open fire-places, which via the chimney stack spread heat down into the suspended foundation. The lowered temperature makes the construction sensitive to moisture attack. There are two main ways by which the moisture can attack the construction, on one hand ground moisture can spread by the air up into the construction and on the other hand air damp can enter by means of the ventilating air.

As the temperature during summer time is lower in the suspended foundation than in the surrounding air the air in the suspended foundation is able to carry a less amount of moisture and thereby the air of the suspended foundation will obtain a higher relative humidity. At 80% relative humidity and above the risk is great for having a mould attack. When the air reaches 100% relative humidity it will moreover condense onto the cold surfaces of the suspended foundation.

Older constructions lack protection against ground moisture, something that one today tries to attend to using sealing layers and capillary interrupting layers. Thus one has to live with the air moisture of a suspended foundation of a construction of today. This makes the suspended foundation is a susceptible construction with accompanying frequent moisture and mould damages.

By closing the ventilation openings the ventilating air can be closed out, but then there is no possibility to ventilate away any present, and from the surroundings added damp this will also lead to high air moisture of the suspended foundation with the accompanying moisture and mould damages. By blowing a heated indoor air into the foundation and isolate the ground, so called warm foundation, the relative humidity can be reduced so much that it falls under the critical level. This technique is however, energy demanding as the crawlway in this way is kept heated. Energy is also consumed to operate the fans and maintenance is required for these. There are also high demands on the fact that the construction is tight and that the air exchange is high enough.

Different methods for preventing moisture in the suspended foundation comprising dehumidiying devices and draining systems are previously known inter alia from patent application SE 468,900, U.S. Pat. No. 4,702,149 and CH patent 370,217.

SE 468,900 discloses a method and a device for avoiding damaging humidity levels at damp sensitive parts of a foundation construction by means of a controlled moisture transport and a controlled condensation. This is done by the air circulation in the space between ground and the floor structure, the so called suspended foundation is prevented by sealing the surrounding constructions and that the space is provided with or is connected to a dehumidifier. The dehumidifier can for example consist of a dehumidifying apparatus and/or a water pipe and/or a closed ventilation system in contact with the outdoor air and/or closed pipe systems having a suitable cooling liquid circulating. These methods mean energy consumption and maintenance of the equipment. As the methods mean that one continuously works against an inbuilt problem, instead of building it away, the methods are sensitive to lack of maintenance and operational disturbances.

For a completely different purpose it is previously known to apply air cushions in a suspended foundation viz for act in an impact reducing and reinforcing way. IP 2001090091 discloses how air cushions, in an emptied condition, are placed into the suspended foundation of a building. The cushions are connected to sensors which detects shakes. The sensor activates a signal in case of an earth quake, when the signal is given the air cushions will be blown up and will dampen or absorb the shakes of the earth quake before it reaches the building. The air cushion is thus only activated in case of an earth quake.

NL 1,014,662 discloses a liquid filled, inflatable cushion being placed in the suspended foundation of a building in order to reinforce weakened concrete floors. To arrange an inflatable cushion in the suspended foundation according to NL 1,014,662 is more efficient and cheaper than to arrange reinforcing pillars.

None of said documents above discloses any method and device where one by installing an air cushion in the suspended foundation of a building can form a moisture barrier against air and ground damp simultaneously as one obtain an improved insulation to cold from the ground.

THE OBJECT OF THE INVENTION AND THE SOLUTION TO THE PROBLEM

It is thus one object of the present invention to provide a method and a device, which at new constructions and in present buildings forms a moisture barrier against air and ground damp and insulates to cold from the ground.

This object is obtained by providing a method and a device according to claims 1 and 10. This results moreover in that energy is saved at the heating of a building and/or that less floor insulation needs to be used, as well. The sealing layers against the ground used in the present constructions can in certain cases be eliminated, as well.

Further embodiments of the present invention are disclosed in the dependent claims.

SHORT DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in more detail by means of a number of embodiments and with reference to the accompanying drawing, in which:

FIG. 1 shows a schematic foundation construction of a building construed according the suspended foundation principle,

FIG. 2 shows a schematic sketch of an expandable device arranged in the foundation construction of FIG. 1 according to a first embodiment,

FIG. 3 shows a schematic sketch of the expandable construction according to a modification of the first embodiment of FIG. 2,

FIG. 4 shows a schematic sketch of the expandable device according to a second embodiment,

FIG. 5 shows a schematic sketch of the expandable device according to a third embodiment.

DESCRIPTION OF EMBODIMENTS

In the following a number of embodiments of the present invention as well as some modifications thereof will be described in detail and with reference to the accompanying drawing. Further examples of other possible embodiments will be described as well.

FIG. 1 shows schematically a foundation construction of a building according to the suspended foundation principle. The suspended foundation comprises a space in the form of a crawl space which is denoted 10 in the drawing. The space 10 is restricted by an upper side 12 being the counter floor of the foundation construction. “The counter floor” is a well known term to the one skilled in the art. The upper side 12 can be an undivided surface. The upper side 12 can also a divided surface, for example if the building is large and/or comprises a lot of angles and corners. The upper side 12 may then comprise two or more restricted surfaces. The space 10 is further restricted by a bottom 14 being the ground which the foundation is construed onto. The bottom 14 may also be an undivided surface or several smaller restricted surfaces. The foundation construction further comprises beams 16 as well as load carrying beams 18. The space 10 is available via one or more openings 19. In FIG. 2 the invention is shown according to a first embodiment. In the space 10 an expandable device 20 is arranged. The term “expandable device” means according to the invention a closed, expandable unit, which can be filled with different filling agents, such as air, gas, foam, and/or the similar. Further, the expandable device 20 can be filled with different gases which react with each other when the expandable device 20 is released, whereby it expands. The expandable device 20 is preferably filled with air and will therefore in the following, for reason of simplicity, be called air cushion.

The air cushion 20 is provided with at least one valve 22. The valve 22 can be of the same type as those car tires are provided with. The valve 22 can also be a more sophisticated valve 22 for a more rapid filling and emptying of the air cushion 20. Further, the air cushion 20 can be arranged with a non-inflatable edge (a border) or the similar (not shown) which abuts the bottom 14 when the air cushion 20 is in place in the suspended foundation 10. The edge can have different functions; inter alia the edge can keep the air cushion 20 in place before it is expanded. The edge may also function as an extra moisture barrier. Further, the air cushion can be anchored to the bottom 14 by means of the edge.

The air cushion 20 is preferably made of one or more materials which are temperature resistant and manage normal temperature differences. The material should be flexible and have a certain grade of toughness. The material should moreover withstand outside damp and should be impermeable or at least restricted permeable to the filling medium, so that the filling medium stays for a long time in the air cushion 20. The material can with advantage be resistant to mould attacks.

Examples of possible materials are rubber materials, such as butyl rubber, natural rubber, isoprene rubber, styrene-butadiene rubber, EPDM, chloroprene rubber or mixtures thereof. The air cushion 20 can also consist of soft thermoplastic materials (TPE materials) such as TPS (styrene based elastomers), TPO (olefin based elastomers), TPV (thermoplastic vulcanisates), TPU (thermoplastic urethanes), TEEE (polyester based elastomers), TPA (amide based elastomers) or mixtures thereof.

Further, the air cushion 20 can consist of plasticized PVC or flexible olefin co-polymers. The construction may also be made in multiple layer structure where one combines several materials and uses their different properties.

In a first embodiment of the invention, cf. FIG. 2, the air cushion 20 is arranged as a substantially continuous fillable unit, which can be filled with air, gas, foam and/or the similar. The air cushion 20 is preferably arranged with two valves 22 one at each end of the air cushion 20 so that one can reach the valves 22 through both openings 19, cf. FIG. 2.

The air cushion 20 may also be deigned in an irregular fashion, cf. FIG. 3. This may be necessary if the space 10 is complicated designed and/or large.

At a new construction the air cushion 20 can be installed at a suitable occasion during the erection process. At the installation in a present building the air cushion 20 can be introduced through one of the openings 19 into the space 10, substantially in a non-expandable condition, which means that the air cushion 20 can be introduced through relatively small openings 19. It may, however, optionally be necessary to widen the opening/openings permanently or occasionally.

When the air cushion 20 is at place in the space 10 it will become expanded so that it substantially fills the whole space 10. The air cushion 20 expands e.g., by means of a pump or the similar. The air cushion 2 may also include an air cylinder (not shown) or the similar which can be triggered by some sort of trigging mechanism, e.g., a rope or a button (not shown). When one tows in the rope or presses the button the air cylinder is released and expands the air cushion 20.

In an expanded condition the air cushion 20 is intended to fill at least a substantial part of the space 10. The term “substantial part” according to the invention shall here mean that at least 50% of the space 10 is filled by the air cushion 20. Preferably at least 75% of the space 10 filled and more preferably 85% and most of all at least 95%. At a construction according to the third embodiment, cf. FIG. 5, the invention may function even if the air cushion 20 fills less than 50% of the space 10.

The shape of the air cushion 20 shall preferably correspond to the form of the actual space 10. Preferably, the air cushion 20 may be somewhat subdimensioned, preferably 0.1 to 10%, rather 1 to 5% to utilize the expansion ability of the material and to avoid formation of wrinkles.

The air cushion 20 is designed in such away that it, to a substantial part abuts closely to the upper side 12. With “substantial part” means, according to the invention, that the air cushion 20 abuts at least 75% of the upper side 12, More preferably the air cushion 20 shall abut 85% of the upper side 12 and still more preferably at least 95%. As the air cushion 20 also abuts the bottom 12 a protection against evaporation ground damp is obtained. Moreover, a permanent protection against the air humidity is obtained, contrary to the solutions known today, as no ventilating air reaches the suspended foundation. The air mass of the air cushion 20 is substantially stationary and will thereby function as an extra insulation. In particular when it is cold outside a favourable temperature profile is obtained inside the air cushion 20 as the floor of the building is warmer than the ground outside. This means that the warmer air lies on the top and thereby is convection avoided, heat transport by means of streaming air or gas, in the air cushion 20, which in turn leads to that the iarc 20 will function as insulation.

The space 10 of the suspended foundation should be construed in such away that any contact between the air cushion 20 and sharp edges, nails or other sharp objects is avoided in order to prevent damages to the air cushion 20 or punctuation of the air cushion 20. In order to form an evener surface and in that way prevent that the air cushion 20 is subject to unnecessary strains a smooth surface 24 can be applied onto the bottom 14. The smooth surface 24 can e.g., be made of macadam, sand or the similar which is poured onto the bottom 14 of the space 10. Alternatively, a cellular plastic sheet or the similar be put onto the bottom 14 for the same purpose.

Damages caused by damp can substantially be prevented according to the present invention by arranging the air cushion 20 to abut closely the upper side 12 and in that it has three functions, the air cushion 20:

-   -   Prevents air humidity from attacking the foundation         construction,     -   Prevents ground moisture from raising into the foundation         construction, and     -   Isolates against cold from the ground.

The insulating effect of the air cushion 20 leads to that the temperature, particularly in the lower part of the floor construction raises. This makes condensation of further moisture more difficult simultaneously as it supports transport upward of moisture through the floor of a building out into the rooms of a building. The isolating ability can also contribute to energy saving at the heating of a building. Alternatively, less insulation may be used in the floor which further raises the temperature of the lower part of the floor and thereby the risk for moisture attack will be reduced still more. The sealing layer against the ground used in the present constructions can be eliminated in certain cases.

As it is possible to empty the air cushion 20 the possibility of repairing the suspended foundation, inspect or add further installations is not prevented. The device according to the present invention can be provided with some type of surveillance system (not shown) which sends of an alarm if the pressure in the air cushion 20 would fall below a certain, predetermined value. Further the device may be supplemented with an automatic pressure regulation (not shown).

In a second embodiment, cf FIG. 4, the air cushion 20 is divided into at least two sections 26. The sections 26 can be filled each per se, independent of each other using air, gas, foam and/or the similar. Each section is provided with at least one valve 22. The sections 26 are releasably, or permanently arranged to each other by means of some type of fastening means (not shown), e.g., Velcro® tape, zip fastener, different types of buttons, e.g., press studs, clips, hooks, different types of tapes, e.g., double sided tape, glue or the similar. The sections 26 may even be arranged independent of each other without any fastening means there between. The sections 26 can be brought together before being expanded or when they have been expanded, depending on size and what is practically utilisable.

In FIG. 5 a third embodiment of the invention is shown. The iarc 20 is arranged in the space 10 in such a way that it abuts the upper side 12. An air gap 28 is left between the air cushion 20 and the bottom 14. In such a way it is avoided that the air cushion 20 is being scratched or damaged in any other way or is punctured by the bottom 14, if the ground should be uneven. The air cushion 20 is provided with some type of fastening means (not shown) to be fastened e.g., to the upper side 12. In such a way the air cushion 20 will abut the upper side 12 and simultaneously leave an air gap 28 to the bottom 14. One or more supporting elements 30, e.g., in the form of supporting wedges or the similar can be arranged to the bottom 14, as well, to support the air cushion 20.

According to a preferred embodiment of the invention it is suitable to design the cushion to the space it is intended to fill up. One can also, to obtain best possible filling, use straps in the corner of the cushion to attach the cushion prior to inflating the same in the suspended foundation in order thereby to guarantee a better mode of filling.

Tests made show, as well, that the cushion should have a volume which is equal to the space to be filled or a volume which exceeds the space to be filled to some percentage, up tp 2%, preferably up to 1%.

The present invention has now been described with reference to to some embodying examples and modifications thereof. The invention is however, not restricted to the embodiments shown but it should be understood that different modifications and supplementations can be made within the scope of the invention as it is defined in the accompanying claims.

REFERENCE NUMBERS

-   Space/crawling space 10 -   Upper side 12 -   Bottom 14 -   Beams 16 -   Load carrying beams 18 -   Opening 19 -   Expandable device/air cushion 20 -   Valve 22 -   Protecting surface 24 -   Section 26 -   Air gap 28 -   Supporting element 30 

1. Method for reducing or substantially prevent admission of moisture to a space (10) of a foundation construction of a building being sensitive to moisture, characterized in that at least one expandable device (20) is introduced into said space (10) of said foundation construction and is brought to expand so that it fills at least a substantial part of said space (10).
 2. Method according to claim 1, characterized in that said expandable device (20) is introduced into said space (10) substantially in a non-expanded condition.
 3. Method according to claim 1 or 2, characterized in that said expandable device (20) is installed in said space (10) and is expanded so that it abuts at least a substantial part of the upper side (12) of said space (10).
 4. Method according to one or more of claims 1-3, characterized in that said expandable device (20) is expanded such that it fills said space (10) to at least 50%, more preferably at least 75% or most preferably at least 95%.
 5. Method according to one or more of claims 1-4, characterized in that said expandable device (20) is installed in said space (10) as a substantially continuous unit, which is filled with air, gas, foam and/or the similar.
 6. Method according to one or more of claims 1-4, characterized in that said expandable device (20) is installed in said space (10) as one or more sections (26), which each is filled with air, gas, foam and/or the similar.
 7. Method according to claim 6, characterized in that said sections (26) are installed releasably arranged to each other in said space (10)
 8. Method according to claim 6, characterized in that said sections (26) are installed independent from each other in said space (10).
 9. Method according to one or more of claims 1-4, characterized in that said expandable device (20) is installed in said space (10) in such a way that an air gap (28) is obtained between the expandable device (20) and a bottom (14) of said space (10).
 10. Device for carrying out the method according to claim 1, characterized by at least one expandable device (20) intended to be introduced in said space (10) of said foundation construction, whereby said expandable device (20) in an expanded condition is intended to fill at least a substantial part of said space (10), said expandable device (20) being made of a material which is impermeable or very restricted permeable to the filling material.
 11. Device according to claim 10, characterized in that said expandable device (20) is designed to abut the upper side (12) of said space (10).
 12. Device according to claims 10 or 11, characterized in that said expandable device (20) is a cushion which can be filled with air, gas, foam and/or the similar.
 13. Device according to claim 12, characterized in that said expandable device (20) is provided with at least one valve (22).
 14. Device according to one or more of the preceding claims, characterized in that said expandable device (20) is arranged as a substantially continuous unit, which can be filled with air, gas, foam and/or the similar.
 15. Device according to one or more of claims 10-13, characterized in that said expandable device (20) is divided into at least two sections (26) which each per se can be filled with air, gas, foam and/or the similar.
 16. Device according to claim 15, characterized in that said sections (26) are releasably arranged to each other by means of at least one fastening means.
 17. Device according to claim 16, characterized in that said fastening means is one of Velcro® tape, zip fastener, button, clips, hook, tape, glue and/or the similar.
 18. Device according to claim 15, characterized in that said sections (26) are permanently arranged to each other.
 19. Device according to claim 15, characterized in that said sections (26) are independently arranged in relation to each other.
 20. Device according to one or more of the preceding claims, characterized in that said expandable device (20) is equipped with a sensor monitoring pressure variations in said expandable device (20) and sends off a signal and/or begins the addition of filling medium to said expandable device if the pressure should be below a predetermined level. 